MEMS devices have been incorporated into personal electronic devices which commonly employ at least one microphone to enable voice communication between the user and the device. In some systems, the MEMS device is an acoustic transducer, deflection by sound waves of a diaphragm within the device results in a change of capacitance which can be measured, interpreted, and translated by the device into a desired output (e.g. a voice command for controlling software on the device). The MEMS device is often enclosed within a frame or package and attached to the interior of the package near a hole or port which allows the interior of the package to communicate with the surrounding environment. Sound thus enters the package through this port and acts upon the MEMS device.
Performance of the MEMS device is vital to successful operation of the system and the electronic device as a whole. With electronic devices becoming part of the day to day lives of most individuals and thus subject to the day-to-day wear and tear that does along with it, maintaining reliability of the devices has become an increasing issue. Given the fragility and sensitivity of the MEMS device, it vital to protect the device from dust, dirt, and any other material or force which could lead to mechanical damage. Further, optimal performance of the device is predicated at least in part on the device's ability to sense the acoustic environment outside (and inside) of the system. Therefore, it is important that the package be designed to prevent potential obstruction of the port and maintain and clear pathway for travel of sound waves and deflection of the diaphragm.
Methods of making generic MEMS device packages are known in the art, such as in United States patent applications US 2014/0246738 and US 2014/0246739, which are incorporated herein by reference in their entireties.
MEMS device packages with increased protection for the MEMS device therein are disclosed in U.S. Pat. Nos. 4,691,363 and 8,130,979, both of which are incorporated herein by reference in their entireties.
U.S. Pat. No. 4,691,363 discloses a MEMS device package including a sound port that is mounted over the passage between the surrounding environment of the package and the MEMS device located within. U.S. Pat. No. 8,130,979 also discloses a MEMS device package where a cap is mounted over the port and provides communication between the surrounding environment and the MEMS device located at the other end of the port.
MEMS device packages with internal structures for preventing flow of material into the acoustic port are disclosed in U.S. Pat. No. 7,537,964, which is incorporated herein by reference in its entirety. U.S. Pat. No. 7,537,964 discloses a MEMS device package that includes an internal retaining ring for preventing wicking of material into the sound port or onto the MEMS device.
Demands on the package housing a MEMS device are stringent. Package designs are progressing in two directions: better performance through optimization of certain design parameters and miniaturization to comply with the spatial constraints of ever more compact electronic devices. Additionally, while the complexity of these devices continues to increase, there is a continued desire to simplify the manufacturing process to keep production costs as low as possible and improve efficiency.
There is a desire, therefore, for a durable MEMS device package which allows for increased design freedom, decreased manufacturing complexity and cost, and improved manufacturing efficiency.